1. Field of the Invention
The invention concerns a device to detect thermal radiation. In addition to the device, a method is specified for the production and a use of the device.
2. Description of the Prior Art
A device to detect thermal radiation is known from DE 100 04 216 A1, for example. This device is designated as a pyrodetector. The detector element is a pyroelectric detector element. It possesses a layer design with two electrode layers and a pyroelectric layer with pyroelectrically sensitive material arranged between the electrode layers. This material is lead zirconate titanate (PZT). For example, the electrodes consist of platinum or of a chromium-nickel alloy absorbing the thermal radiation.
The thermal detector element is connected with a detector element substrate made of silicon (silicon substrate). An insulation layer for electrical and thermal insulation of the detector element and the detector element substrate from one another is arranged between said detector element and the detector element substrate. The insulation layer thereby possesses: an evacuated void that extends across a base surface of the detector element; a support layer of the void; and a cover of the support layer and the void. The support layer consists of polysilicon. The cover is made of a boron-phosphorus-silicate glass (BPSG). A readout circuit is integrated into the detector element substrate to read out, process and/or relay the electrical signal generated by the detector element. The readout circuit is realized via the CMOS (Complementary Metal Oxide Semiconductor) technique.
A device comparable to this for the detection of thermal radiation is known from DE 195 25 071 A1. The thermal detector element is likewise a pyroelectric detector element described above. The detector is arranged on a multi-layer detector element substrate. One of the layers of the detector element substrate is an electrically insulating membrane. The membrane consists of a Si3N4/SiO2/Si3N4 triple layer, for example. The membrane is in turn applied on a silicon substrate of the detector element substrate.
In the known devices a number of detector elements are present (detector element array). In order to obtain an optimally high spatial resolution, the detector elements are arranged optimally close to one another. However, the more closely that the detector elements are arranged, the higher the probability of a “crosstalk”. The desired high resolution is lost.